Rubber composition for conveyor belt, and conveyor belt

1. A rubber composition for a conveyor belt comprising: a diene rubber and a carbon black,

the diene rubber containing:

a natural rubber; and

a modified butadiene rubber obtained by modifying a butadiene rubber with a nitrone compound;

a content of the natural rubber in the diene rubber being 30 to 85 mass %, and a content of the modified butadiene rubber in the diene rubber being 15 to 70 mass %.

2. The rubber composition for a conveyor belt according to claim 1 , wherein the nitrone compound contains a carboxy group.

3. The rubber composition for a conveyor belt according to claim 1 , wherein a content of the carbon black is from 20 to 50 parts by mass per 100 parts by mass of the diene rubber.

4. The rubber composition for a conveyor belt according to claim 1 , wherein a nitrogen adsorption specific surface area of the carbon black is from 25 to 100 m 2 /g.

5. The rubber composition for a conveyor belt according to claim 1 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

6. The rubber composition for a conveyor belt according to claim 1 , wherein a degree of modification of the modified butadiene rubber is from 0.02 to 4.0 mol %, where “degree of modification” refers to a proportion (mol %) of double bonds modified with the nitrone compound to all the double bonds contained in the butadiene rubber.

7. A conveyor belt comprising the rubber composition for a conveyor belt described in claim 1 as a lower cover rubber layer.

8. The rubber composition for a conveyor belt according to claim 2 , wherein a content of the carbon black is from 20 to 50 parts by mass per 100 parts by mass of the diene rubber.

9. The rubber composition for a conveyor belt according to claim 2 , wherein a nitrogen adsorption specific surface area of the carbon black is from 25 to 100 m 2 /g.

10. The rubber composition for a conveyor belt according to claim 3 , wherein a nitrogen adsorption specific surface area of the carbon black is from 25 to 100 m 2 /g.

11. The rubber composition for a conveyor belt according to claim 8 , wherein a nitrogen adsorption specific surface area of the carbon black is from 25 to 100 m 2 /g.

12. The rubber composition for a conveyor belt according to claim 2 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

13. The rubber composition for a conveyor belt according to claim 3 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

14. The rubber composition for a conveyor belt according to claim 4 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

15. The rubber composition for a conveyor belt according to claim 8 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

16. The rubber composition for a conveyor belt according to claim 9 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

17. The rubber composition for a conveyor belt according to claim 10 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

18. The rubber composition for a conveyor belt according to claim 11 , wherein the nitrone compound is a compound selected from the group consisting of N-phenyl-α-(4-carboxyphenyl)nitrone, N-phenyl-α-(3-carboxyphenyl)nitrone, N-phenyl-α-(2-carboxyphenyl)nitrone, N-(4-carboxyphenyl)-α-phenylnitrone, N-(3-carboxyphenyl)-α-phenylnitrone, and N-(2-carboxyphenyl)-α-phenylnitrone.

19. The rubber composition for a conveyor belt according to claim 2 , wherein a degree of modification of the modified butadiene rubber is from 0.02 to 4.0 mol %, where “degree of modification” refers to a proportion (mol %) of double bonds modified with the nitrone compound to all the double bonds contained in the butadiene rubber.

20. The rubber composition for a conveyor belt according to claim 3 , wherein a degree of modification of the modified butadiene rubber is from 0.02 to 4.0 mol %, where “degree of modification” refers to a proportion (mol %) of double bonds modified with the nitrone compound to all the double bonds contained in the butadiene rubber.